Total iron-binding capacity (TIBC) is an indicator of your body’s iron levels. Keep reading to learn more about high and low levels and what they mean for your health, as well as how to improve TIBC.
What is Total Iron-Binding Capacity (TIBC)
Total iron-binding capacity (TIBC) measures the total capacity of your blood to bind and transport iron. It is used to estimate the amount of iron stored in your body [1, 2].
TIBC is an indirect measure of transferrin, a protein that binds iron molecules and transports them in the bloodstream. Transferrin is produced in the liver and is the main iron-binding protein in the blood [3, 4].
TIBC is most often used to check for iron deficiency.
Because they measure the same thing TIBC and transferrin tests are redundant. It’s enough to measure one of them. TIBC is cheaper, but transferrin is preferable because it has a well established and more accurate range. TIBC may, however, be a better measure in populations that have high frequencies of transferrin genetic mutations [3].
Similarly, because they both measure iron stores in the body, if your ferritin levels are already available, TIBC levels may be redundant and unneeded when testing for iron deficiency [5].
Some laboratories also provide UIBC or unsaturated iron binding capacity, which is the number of transferrin sites not carrying iron [6].
TIBC Normal Range
The normal range of TIBC is between 250 – 450 μg/dL (micrograms per deciliter) which corresponds to 44.8 – 80.5 μmol/L (micromoles per liter).
Low TIBC Levels
Causes of Low TIBC
Causes shown below are commonly associated with low TIBC. Work with your doctor or another health care professional to get an accurate diagnosis. Your doctor will interpret your TIBC value, taking into account your medical history, symptoms, and other test results.
1) Excess Iron Levels (Iron Overload)
The most common cause of low TIBC is excess iron in the body [7].
Iron overload can happen due to poisoning, or in some hereditary disorders, such as hemochromatosis, thalassemia, or sickle cell anemia [7, 8].
However, not everyone with iron overload will have low TIBC. A lot of people with iron overload will have TIBC in the normal range [9].
2) Inflammation
Transferrin is a negative acute phase protein. This means that in inflammation, as the liver increases the production of inflammation-associated proteins (e.g. CRP, ferritin) it decreases the production of transferrin. As transferrin decreases, so does iron binding capacity and therefore TIBC [10, 11].
TIBC is decreased in people who have anemia of inflammation also known as anemia of chronic disease [12, 2]. This type of anemia is caused by inflammatory cytokines and associated with underlying conditions such as infections, inflammatory disease, autoimmune disease, and cancer [13].
3) Liver Disease
The liver helps keep iron levels in balance. During liver diseases and injury, more iron is absorbed in the gut, causing TIBC to decrease [14, 15].
Also, in liver disease, the liver can’t produce transferrin effectively, which decreases total iron-binding capacity [16].
4) Malnutrition
TIBC levels can be low in malnutrition [8].
5) Kidney Disease
Low TIBC can also be caused by kidney disease accompanied by protein loss (wasting) [11, 17].
6) Hemolysis
Abnormal destruction of red blood cells (hemolysis) [8].
Health Effects of Low TIBC
1) Is Associated With A Higher Heart Attack Risk
High iron levels are a risk factor for heart attack. In an observational study of over 2,000 people, low TIBC was associated with an increased risk for heart attacks over the next 8 year follow-up period. Each increase in TIBC of 1 μmol/L was associated with a 5% decrease in heart attack risk [18].
2) Is Associated With Higher Cancer Risk
In a study with over 41,000 people, lower TIBC was associated with a higher lung cancer risk over the 14-year follow-up [19].
In another study of 700+ people, lower TIBC was associated with a higher risk of colon cancer [20].
Increasing TIBC
The most important thing is to work with your doctor to find out what’s causing your low TIBC and to treat any underlying conditions. The additional lifestyle changes listed below are other things you may want to discuss with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!
The following are ways to increase TIBC by decreasing your iron levels when they are high. Other than that, you can only correct low TIBC levels by addressing and resolving the underlying condition/disease.
1) Exercise
If your iron is high, you can get more exercise. Regularly exercising can help prevent iron levels from becoming too high, as well as TIBC from decreasing [21, 22].
2) Diet
If you have high iron levels, you should avoid foods that are high in iron, such as red meat, fish, and poultry. You should also eat foods that reduce iron absorption, including fiber, phytic acid (from whole grains), and chili [23, 24, 25, 26].
Beverages such as coffee, cocoa, green tea, and herbal teas (chamomile, lime flower, penny flower, mint, and vervain) can also reduce iron absorption [27, 28, 29, 30, 31, 32, 33].
High TIBC
Causes of High TIBC
Causes shown below are commonly associated with high TIBC. Work with your doctor or another health care professional to get an accurate diagnosis. Your doctor will interpret your TIBC value, taking into account your medical history, symptoms, and other test results.
1) Iron Deficiency
TIBC increases during iron deficiency [7].
Iron deficiency can be due to dietary deficiency, bleeding (e.g. menstrual bleeding or ulcers), and gut disorders that decrease iron absorption (e.g. celiac disease) [7].
A study suggests that pregnant women may also commonly experience iron deficiency due to low dietary intake and higher demand, especially during the third trimester [34].
2) Polycythemia vera
Polycythemia vera is a disease in which the bone marrow makes too many red blood cells that use up a lot of iron. Polycythemia vera patients may have a functional iron deficiency, which can increase TIBC [8].
Health Risks of High TIBC
High TIBC is Associated with Celiac Disease Risk
Abnormal iron levels may play a role in celiac disease development. Alternatively, they may be an early sign of the disease, before it can be diagnosed by other means.
In a study of 852 people, a high TIBC level was associated with an increased risk of developing celiac disease. For each 10 μg/dL increase in TIBC, the risk of celiac disease increased by 4.6, 3.8, and 7.9% within 1, 1 – 3, and 3 – 5 years prior to diagnosis, respectively [35].
Decreasing TIBC
The most important thing is to work with your doctor to find out what’s causing your high TIBC and to treat any underlying conditions. The additional lifestyle changes listed below are other things you may want to discuss with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!
1) Iron-rich Diet
Eating a diet high in iron can help prevent iron deficiency. Foods that contain a lot of iron include red meat, poultry, fish, tofu, tempeh, nuts, and seeds [23].
Avoid drinking coffee, cocoa, green and herbal teas with food, as these decrease iron absorption from food [27, 28, 29, 31, 32, 33].
Vitamin C helps increase iron absorption [36]. You can include more vitamin-C rich foods (e.g citrus fruits, sauerkraut) with your iron-rich meals.
However, keep in mind that iron deficiency can be caused by an underlying health issue, in which case it can’t be reversed by dietary modifications alone.
2) Supplements
If you have an iron deficiency, iron supplements will increase your iron levels. They are, however, associated with a lot of side effects. You also don’t want to overdo them, because iron overload increases oxidative stress in the body and has a lot of negative consequences. You may want to try and correct a mild efficiency through dietary intervention first [37, 38, 39].
For severe cases, your doctor may prescribe iron supplements or injections.
